In a known image processing technique, a high quality image is obtained by performing image processing on image data based on pixel attribute per pixel. The pixel attribute is pixel additional information indicating, for example, whether the pixel to be image processed belongs to a character area or a photographic area. A pixel having a character attribute is subjected to image processing for character, while a pixel having a photograph attribute, to image processing for photograph. In this manner, optimum image processing is performed in correspondence with pixel attribute.
Hereinbelow, the conventional construction for image processing in correspondence with pixel attribute will be described with reference to FIG. 5.
In FIG. 5, an image processing apparatus comprises m image processors 301, 302, . . . , and 303. In each image processing unit, a predetermined pixel attribute is referred to, and image processing corresponding to the pixel attribute is performed. That is, the image processing units refer to respectively different pixel attributes.
In the figure, an input image is first subjected to image processing based on a pixel attribute 1 by the image processing unit 301. The output from the image processing unit 301 is inputted into the image processing unit 302 and similarly subjected to image processing based on a pixel attribute 2. Hereinafter, through image processing based on the predetermined pixel attributes, the image is finally subjected to image processing based on pixel attribute 3 and pixel attribute 4 by the image processing unit 303.
Accordingly, as a finally-obtained output image, a high quality image appropriately reflecting attributes of respective pixels is obtained.
However, the above conventional image processing apparatus has the following problems.
In the image processing apparatus in FIG. 5, in a case where the pixel attribute to be referred to in the image processing unit 301 is changed from the pixel attribute 1 to, for example, the pixel attribute 2, or image processing is performed based on the result of calculation between the pixel attribute 1 and the pixel attribute 3 will be studied, if the image processing unit 301 is already realized by hardware as e.g. a semiconductor integrated circuit, change in connection or the like or addition of calculation circuit are difficult. Accordingly, such correction cannot be made.
Further, in a case where product specifications are uncertain in the middle of product development, as development of the image processing unit for processing based on pixel attribute cannot be started, the entire development schedule is delayed.